The purpose for artists being driven to create art for many different reasons seems to for an aesthetic purpose. This looked to be the purpose of Edvard Munch when he created his masterpiece in 1893, named the Starry Night. The subject of this work is the division of the water, earth, and sky but rejoins in a huge unity.
Value is a dark or light scale.
So it would be C. The lightness or darkness of a color.
Art has VISUAL form, which includes the materials used to make the artwork, its formal elements, and its overall composition.